Epitaxial graphene on SiC: modification of structural and electron transport properties by substrate pretreatment.

The electrical transport properties of epitaxial graphene layers are correlated with the SiC surface morphology. In this study we show by atomic force microscopy and Raman measurements that the surface morphology and the structure of the epitaxial graphene layers change significantly when different pretreatment procedures are applied to nearly on-axis 6H-SiC(0 0 0 1) substrates. It turns out that the often used hydrogen etching of the substrate is responsible for undesirable high macro-steps evolving during graphene growth.

Versatile sputtering technology for AlO gate insulators on graphene.

We report a novel, sputtering-based fabrication method of AlO gate insulators on graphene. Electrical performance of dual-gated mono- and bilayer exfoliated graphene devices is presented. Sputtered AlO layers possess comparable quality to oxides obtained by atomic layer deposition with respect to a high relative dielectric constant of about 8, as well as low-hysteresis performance and high breakdown voltage.

AFM diagnostics of graphene-based quantum Hall devices.

In this paper we present the results of morphological, mechanical and electrical investigation of the properties of prepared graphene flakes and graphene-based quantum Hall devices. AFM imaging allowed us to identify the local imperfections and unintentional modifications of the graphene sheets which had caused severe deterioration of the device electrical performance. Utilizing the NanoSwing imaging method, based on the time-resolved tapping mode, we could observe non-homogeneities of the structural and mechanical properties.